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    When asked to work out Kc, in which situations do u divide by the volume? or do you always divide by the volume given :confused:
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    I'm not quite sure I follow, but if you mean when does volume of the solution not matter - ir's when you have equal numbers of molecules on each side of the equilibrium:

    A + B <---> C + D then K_c = \frac{[C][D]}{[A][B]} so the volumes cancel

    but when this isn't the case e.g.

    A + B <---> C then K_c = \frac{[C]}{[A][B]} then the volumes don't cancel

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    Oh i see.
    Thank you very much
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    Just to be safe always use the volumes if given! Get in the habit of including volumes in your calculations, because if you forget to include them and they don't cancel out your answer will be wrong and you'll lose most of the marks.

    In some cases they will cancel as explained above.
 
 
 
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